Inflatable device with exhausting apertures which vary in density

ABSTRACT

A thermal blanket includes an inflatable covering with a head end, a foot end, two edges and an undersurface. The covering is inflated through an inlet at the foot end by a thermally-controlled inflating medium. An aperture array on the undersurface of the covering exhausts the thermally-controlled inflating medium from the covering. Exhaust port openings are provided at the edges of the covering to vent the inflating medium, which enhances circulation of the thermally-controlled medium through the cover. An uninflatable section is provided at the head end, together with an absorbent bib attached to the covering, adjacent the uninflatable section. When inflated, the thermal blanket self-erects and provides a bath of thermally-controlled inflating medium to the interior of the erected structure. The enhanced circulation of the medium through the covers maintains a relatively high average temperature under the blanket and a relatively uniform distribution of temperature in the inflating medium which is exhausted through the apertures into the structure&#39;s interior. When the structure covers a patient, the uninflatable section provides a relatively unobstructed view of the patient&#39;s face, while the absorbent bib maintains a relatively sanitary environment in the area beneath the patient&#39;s head.

BACKGROUND OF THE INVENTION

[0001] This invention relates to thermal blankets used in a medicalsetting to deliver a bath of a thermally-controlled medium to a patient.

[0002] The thermal blanket prior art is best expressed in our prior U.S.Pat. No. 4,572,188 entitled “AIRFLOW COVER FOR CONTROLLING BODYTEMPERATURE.” In our prior patent, a self-erecting, inflatable airflowcover is inflated by the introduction into the cover of athermally-controlled inflating medium, such as warmed air. Wheninflated, the cover self-erects about a patient, thereby creating anambient environment about the patient, the thermal characteristics ofwhich are determined by the temperature of the inflating medium. Holeson the underside of our prior art airflow cover exhaust thethermally-controlled, inflating medium from inside the cover to theinterior of the erected structure. Our airflow cover is intended for thetreatment of hypothermia, as might occur post-operatively.

[0003] Evaluation of our airflow cover by skilled practitioners hasresulted in general approbation: the opinion is that the airflow coverefficiently and effectively accomplishes its purpose of giving athermally-controlled bath. We have realized, however, that, while ourprior art airflow cover achieves its objective, certain improvements toit are necessary in order to realize additional clinical objectives andto enjoy further advantages in its use.

SUMMARY OF THE INVENTION

[0004] We have improved the clinical usefulness of our self-erectingairflow cover by observing that controlling the contour of itsinflatable portion at its head end to define a generally concavenon-inflatable portion will permit a care giver to more easily observe apatient's head, face, neck and chest. Further, we have observed thatlimited venting of the thermally controlled inflating medium from theedges of the cover results in more efficient, more uniform heatingwithin the cover. We have also observed that it is good clinicalpractice to keep the area of the care site in the vicinity of thepatient's head and face as clean as possible.

[0005] These three observations have resulted in an improved thermalblanket in which a self-erecting inflatable covering has a head end, afoot end, two edges, and an undersurface. An inflating inlet adjacentsaid foot end admits a thermally-controlled inflating medium into thecovering. An aperture array on the undersurface of the covering exhauststhe thermally-controlled inflating medium from the covering into thestructure created when the covering self-erects upon inflation. Theimprovements to this basic structural complement include an uninflatablesection at the head end of the covering, exhaust port openings at theedges of the covering, an absorbent bib attached to the covering at thehead end adjacent the uninflatable section, and structural features thatmake the covering simple and economical to produce.

[0006] With these improvements, the thermal blanket, when inflated anderected over a patient, delivers the thermally-controlled inflatingmedium into the interior of the structure covering the patient, therebythermally bathing the patient. The first improvement permits fullviewing of the head and face of the patient from almost any aspectaround the thermal blanket. The exhaust port openings increase the rateof circulation of the inflating medium within the blanket, therebyincreasing the temperature within the structure and making thetemperature distribution more uniform. The absorbent bib soaks up andretains liquids which might otherwise spread over the care site in thearea of a patient's head. Such liquids can include the patient's ownperspiration, blood, vomit, saliva, or liquids which are administered tothe patient. The absorbent bib also acts to some extent to seal the headend of the inflated structure.

[0007] From another aspect, the invention is a thermal blanket forcovering and bathing a person in a thermally-controlled medium. Thethermal blanket includes a flexible base sheet having a head end, a footend, two edges, and a plurality of apertures opening between the firstand second surface of the base sheet. An overlying material sheet isattached to the first surface of the base sheet by a plurality ofdiscontinuous seams which form the material sheet into a plurality ofsubstantially parallel, inflatable chambers. A continuous seam isprovided between the material sheet and the base sheet at the head endto form a non-inflatable viewing recess at the head end. Exhaust portopenings are provided through the material sheet to vent the medium fromthe chambers away from the base sheet. An absorbent bib is attached tothe head end in the vicinity of the viewing recess.

[0008] Therefore the invention accomplishes the important objective ofproviding a self-erecting, inflatable thermal blanket that permits arelatively unobstructed view of a patient's head and face when in use.

[0009] Another objective is the efficient and uniform heating of theinterior of the structure created when the blanket is inflated with aheat inflating medium.

[0010] A signal advantage of the invention is the provision of such ablanket with a means for maintaining the cleanliness of the care site inthe vicinity of the patient's head and face.

[0011] The advantageous simplified structure of the thermal blanket makeits production straightforward and economical.

[0012] These and other important objectives and advantages will becomeevident when the detailed description of the invention is read withreference to the below-summarized drawings, in which:

[0013]FIG. 1 is a side elevation view of the thermal blanket in use,with associated thermal apparatus indicated schematically;

[0014]FIG. 2 is an enlarged top plan view of the thermal blanket openedflat;

[0015]FIG. 3 is an enlarged sectional view taken along 3-3 of FIG. 2;

[0016]FIG. 4 is a further enlarged sectional view taken along line 4-4of FIG. 3; and

[0017]FIG. 5 is a partial underside view of the thermal blanket.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] When used herein, the term “thermal blanket” is intended to beinterchangeable with, but not necessarily limited by, the term “airflowcover” used in our U.S. Pat. No. 4,572,188, which is incorporated hereinin its entirety by reference. In this description, the term “thermalblanket” is meant to invoke a self-erecting, inflatable structure fordelivering a thermally-controlled inflating medium to the interior ofthe structure created when the thermal blanket is inflated. The purposeof the thermal blanket is to efficiently administer a uniformlythermally-controlled bath of the inflating medium to a patient withinthe erected structure.

[0019] Our invention is illustrated as we intend for it to be used inFIG. 1. In FIG. 1, a self-erecting, inflatable thermal blanket 10 has ahead end 12, a foot end 14 and two lateral edges, one indicated by 15.An inflation inlet cuff 16 is connected to a heater/blower assembly 18which provides a stream of heated air through a connecting hose 20. Whenthe heater/blower 18 is operated, the stream of heated air flows throughthe inflating hose 20 into the thermal blanket 10 through the inflationcuff 16. When the blanket is inflated, it erects itself into a Quonsethut-like structure with a quilted upper surface 21. As described below,a pattern of apertures on the undersurface of the blanket (not shown inFIG. 1) delivers the inflating heated air into the interior spaceenclosed by the erected thermal blanket.

[0020] The contour of the inflatable portion of the thermal blanket 10is varied at the head end 12 of the blanket to provide a non-inflatedblanket recess 22 in the quilted upper surface 21, which remains smoothand flat when the blanket is inflated and erected. Circulation of theheated air is accelerated through the thermal blanket by exhaust portopenings in the upper surface, adjacent the lateral edges of theblanket. Two exhaust port openings are indicated by reference numeral23. Further, a bib 24 made of an absorbent material is attached to thehead end 12 of the thermal blanket in the vicinity of the non-inflatedrecess 22. In fact, as shown in FIG. 1, the bib 24 includes asemi-circular tab 25 that extends into the recess 22.

[0021] As illustrated in FIG. 1, the thermal blanket of the invention isinflated, erects itself into a bathing structure, and bathes a patient26 with the thermally-controlled air used to inflate the structure.While the patient is being thermally bathed, the uninflated recess 22permits observation of the patient's head, face, neck, and chest fromalmost any location with respect to the thermal blanket 10. Thus, if thepatient is placed on a gurney or a bed, the head of which is against awall, a care giver such as a nurse, intern, resident, or doctor, cankeep the patient's face under observation from the foot end 14 of thethermal blanket 10. Respiration can be detected by the rise and fall ofthe bib and uninflated area, which rest directly on the patient's chest.Moreover, the bib 24 will provide an absorbent sink for stray,unconfined liquids in the area of the patient's head or at the head end12 of the thermal blanket 10.

[0022]FIG. 2 is a plan view of the thermal blanket 10 opened flat toshow details of its structure. FIG. 2 illustrates the upper surface ofthe thermal blanket, that is the side that is visible in FIG. 1. Asseen, the upper surface consists of a parallel array of elongated tubesof which 30 and 32 are the lateralmost tubes, 34 is the center tube, andthe tubes 38 are arrayed between one of the lateralmost tubes and thecenter tube. Each tube is separated from an adjacent tube by adiscontinuous seam, one of which is indicated by 40. The seam 40separates the tube 32 and its nearest adjacent neighbor 38. Thediscontinuous seam 40 is interrupted by passageways 42 communicatingbetween the tubes. An interrupted seam separates every tube from oneadjacent neighboring tube. The seams permit the thermal blanket, wheninflated, to assume a tubular structure on the upper surface, while theports 42 permit full circulation of the inflating medium throughout thearray of tubes. The foot-end seam 45 is continuous. The tubes areinflated through the center tube 34 which transitions to a port 36,through which the inflation cuff 16 is inserted. The edge seams 43 arediscontinuous only at the exhaust port opening locations 23. A seal canbe made between the inflation port 36 and the inflation cuff 16 by anyconventional means, for example, an O-ring, or even tape. When theinflating medium is introduced into the center tube 34, it flowslaterally from the center tube into all of the other tubes through theports 42. Near the head end 12, a continuous seam 40 defines the forwardend of all of the tubes, with the seam assuming a bell-curve shape. Onthe head end side of the seam 40, the thermal blanket 10 isuninflatable. The bell-shaped seam 40 thus defines the uninflatable area22 at the head end of the thermal blanket 10, which is essentiallycoplanar with, or substantially parallel to, the underside of theblanket. As shown in FIG. 1, by virtue of its structural integrationwith the rest of the thermal blanket 10, the non-inflated recess extendsover the upper chest of the patient 26 when the blanket is inflated.However, since the recess 22 is uninflated, it provides a wide-angledviewing gap in the inflated contour of the upper surface 21. The gap isfilled by continuation of the underside of the blanket. It is also notedthat the pattern of inflatable tubes can be replaced by other suitablepatterns of communicating, inflatable chambers. The tubes are preferredsince they impart strength and shape to the erected bathing structure;other inflatable structures are contemplated, however.

[0023] The absorbent bib has an indent 43 cut into its outside edge,which permits the blanket to be drawn up to the chin of a patient andwhich provides absorbency laterally up the neck of the patient. Theabsorbent bib can consist of any absorbent material such as a single- ormulti-ply tissue paper which is used to make paper towels.

[0024] Construction details of the thermal blanket 10 are illustrated inFIGS. 3 and 4. The thermal blanket 10 is assembled from a base sheetconsisting of an underside layer 50 formed from flexible materialcapable of bonding to a layer 52 of heat-sealable plastic. For thelayers 50 and 52, we have used a stratum of absorbent tissue paperprelaminated with a layer of heat-sealable plastic. Material of suchconstruction is commercially available in production rolls and is usedto make painters' drop cloths. The upper side of the thermal blanketconsists of a sheet of plastic bonded to the plastic layer 52 by aninterruptible heat-sealing process to form the interrupted seams, one ofwhich is indicated by 54, and the inflatable tubes, one indicated by 55.As can be seen in FIG. 3, the interruption of the seam 54 forms apassageway 56 between adjacent tubes 55 and 57.

[0025] The absorbent bib and tab are shown in FIG. 3 as a singlematerial layer 60/58. Alternatively, they may be formed from separatematerial sheets cut to the outlines illustrated in FIG. 2. The absorbentmaterial forming the bib and tab can be bonded to the upper plasticlayer by heat process or by gluing.

[0026] The inventors also contemplate deletion of the bib and tab. Inthis instance, the thermal blanket would still have the viewing recess,which would be defined by the continuous seam at the head end, and whichwould be filled with the forward portion of the base sheet.

[0027] Circulation of heated air through the blanket is enhanced by theexhaust port openings 23, which open through the upper plastic sheetsheet, which is heat sealed to the base of the blanket. The openings 23vent the heated inflating air out of the outermost tubes 30 and 32, awayfrom the underside of the blanket. Because air can circulate to, andthrough, the blanket edges, the inflating air in the outermost tubes ishotter than if the openings were absent. This results in hotter airbeing delivered through the underside apertures toward the edge of theblanket. We have measured the temperature distribution within thethermal blanket for inflating air which is heated to a mediumtemperature range and for inflating air which is heated to a hightemperature range. The results are provided in Table I for a blanketconsisting of 13 tubes. Measurements of the temperature of air exhaustedthrough underside apertures were made on the underside of each tube onone side of the blanket. The tubes are numbered 1-6, with 1 being thetube adjacent to the center tube, and tube 6 being the outermost tubeadjacent on lateral edge of the blanket. Test apertures were made in thebottom of tube 6 only for the purposes of this test. As is evident, thedistribution of temperature within the erected thermal blanket is moreuniform when the exhaust port openings are provided. Further, provisionof the exhaust ports also increases the average temperature within theerected structure of the blanket. Clearly, the provision of exhaust portopenings at the lateral edges of the blanket delivers results which onewould not expect when considering the operation of our thermal blanketwith no exhaust port openings.

[0028] In our preferred embodiment, the exhaust port openings are slitsin the edge seams of our blanket. These slits vary in length from 1¾ to2 inches. Each edge seam is discontinuous approximately at each cornerof the blanket so that inflating air is vented away from the undersideof the erected blanket. This keeps the relatively “colder” air at theblanket edges from mixing with the relatively “hotter” air exhaustedinto the structure through the underside apertures. The result is a“flatter” temperature profile of air within the blanket than without thevents, which raises the average temperature within the erected structureand makes the temperature distribution in the structure more uniform.Resultantly, the clinical effect of the blanket is enhanced. Heating isbetter controlled, and more uniform, with greater comfort to thepatient. TABLE I MEDIUM TEMPER- HIGH TEMPER- ATURE RANGE ATURE RANGEWITHOUT WITH 2″ WITHOUT WITH 2″ EXHAUST EXHAUST EXHAUST EXHAUST TUBE NO.PORTS PORTS PORTS PORTS center (inlet) 113.3° F. 114.1° F. 121.3° F.121.3° F. tube Tube #1 109.9° 112.3° 117.3° 117.7° Tube #2 105.3° 109.8°113.4° 115.0° Tube #3 103.2° 107.1° 111.0° 113.3° Tube #4  99.9° 104.3°101.4° 108.6° Tube #5  97.2° 100.0°  95.7° 104.4° Tube #6  85.2°  95.8° 89.6°  99.4° (outermost) Average 103.8° 106.7° 108.4° 112.5° temp.under cover

[0029] The thermal blanket of the invention is enabled to bathe apatient in the thermally-controlled inflating medium introduced into theupper side tubes by means of a plurality of apertures 62 shown in FIGS.4 and 5. The apertures extend through the underside of the blanket,which includes the layers 50 and 52. The apertures 62 are made in thefootprints of the tubes of the blanket upper side according to a patternwhich has been determined to deliver a very uniform thermal bath. Inthis regard, no apertures are provided through the underside into thelateralmost tubes 30 and 32, or into the center tube 34. In addition,the apertures 62 are provided through the underside to the aperturedtubes in a density which varies inversely with the proximity of the tubeto the center tube 34. Thus, the hole density increases from the tube 38a through the tube 38 d. Even with the exhaust port openings, thetemperature of the inflating medium exhibits a drop from the center tothe lateralmost tubes. The varying density of the apertures 62 tends toreduce this gradient further by forcing hotter air to the edges of theblanket. Thus, the thermal bath delivered to the patient is of agenerally uniform temperature. The aperture density variation alsoequalizes the flow of inflating medium out of the apertures. As will beevident, the inflating pressure will be greatest at the center tube 34and will tend to diminish toward the lateral edges of the thermalblanket. Therefore, fewer apertures are required for the tubes near thecenter tube 34 to deliver the same amount of air as the relativelygreater number of apertures in the tubes at a greater distance from thecenter tube 34.

[0030] The apertures comprise openings which can be of any appropriateshape. For example, we have produced blankets with elongated apertures,approximately ¼ inch in length.

[0031] Many modifications and variations of our invention will beevident to those skilled in the art. It is understood that suchvariations may deviate from specific teachings of this descriptionwithout departing from the essence of the invention, which is expressedin the following claims.

We claim:
 1. A thermal blanket for covering and bathing a person in athermally-controlled inflating medium, comprising: a flexible base sheethaving a head end, a foot end, two edges, and a plurality of apertures;an overlaying flexible material sheet attached to a first surface ofsaid base sheet by a plurality of discontinuous seams which form saidoverlaying material sheet into a plurality of communicating, inflatablechambers, said apertures opening through said base sheet into saidchambers; and a continuous seam between said overlaying material sheetand said base sheet at said head end which forms a non-inflatableviewing area in said blanket at said head end, said non-inflatableviewing area being substantially coplanar with, or parallel to, saidbase sheet.
 2. The thermal blanket of claim 1 wherein said base sheetincludes an undersheet of flexible fibrous material and a sheet ofplastic material coextensive with and attached to said undersheet. 3.The thermal blanket of claim 1 wherein said base sheet includes amulti-layered structure in which the bottommost layer is a paper sheetbonded to an upper sheet of plastic material.
 4. The thermal blanket ofclaim 2 wherein said discontinuous seams are substantially elongate,formed seals between said overlaying material sheet and sheet of plasticmaterial.
 5. The thermal blanket of claim 2 wherein one of saiddiscontinuous seams includes a sequence of collinear, formed sealsextending from said foot end to said head end.
 6. The thermal blanket ofclaim 5 wherein said plurality of discontinuous seams form saidoverlaying material sheet into a plurality of mutually parallel,communicating tubular chambers.
 7. The thermal blanket of claim 1including an exhaust port opening through said material sheet adjacentone of said edges for venting an inflating medium from said chambers andaway from said base sheet.
 8. The thermal blanket of claim 1 including apatterned array of apertures opening through said underside into saidchambers, said patterned array comprising a density pattern in which thedensity of said apertures increases toward one of said edges.
 9. Thethermal blanket of claim 6 including a patterned array of apertures,said apertures opening through said base sheet into said chambers, saidpatterned array comprising a density pattern in which the density ofsaid apertures increases toward on of said edges.
 10. The thermalblanket of claim 9 wherein one of said tubular chambers is centrallypositioned in said parallel tubular chambers and said density increasesfrom said centrally positioned chamber toward one of said edges.
 11. Thethermal blanket of claim 10 wherein no apertures open through said basesheet into said centrally positioned tubular chamber.
 12. The thermalblanket of claim 11 wherein no apertures open through said base sheetinto a tubular chamber adjacent one of said edges.
 13. A thermalblanket, comprising: a self-erecting inflatable covering with a headend, a foot end, two edges, and an undersurface; an inflating inletadjacent said foot end for admitting a thermally-controlled inflatingmedium; an array of apertures in said undersurface for exhausting athermally controlled inflating medium from said covering; an exhaustport opening in said inflatable covering for venting an inflating mediumfrom adjacent an edge of said inflatable covering and away from saidundersurface; and a flat uninflatable section at said head end for upperbody viewing.
 14. The thermal blanket of claim 13 , wherein said patternof said array of apertures increases the density of said apertures froma central location on said undersurface in a direction toward a firstone of said edges.
 15. The thermal blanket of claim 14 wherein thepattern of said array of apertures increases the density of saidapertures from said central location in a direction toward the second ofsaid edges.
 16. A thermal blanket for covering and bathing a person in athermally-controlled medium, comprising: a flexible base sheet having ahead end, a foot end, two edges, and a plurality of apertures; anoverlaying plastic sheet attached to a first surface of said base sheetby a plurality of discontinuous seams which form said plastic sheet intoa plurality of communicating inflatable chambers, said apertures openingthrough said base sheet into said chambers: a continuous seam betweensaid plastic sheet and said base sheet at said head end which forms anon-inflatable viewing recess; and an exhaust vent through saidoverlaying plastic sheet and adjacent a first, opening from a firstinflatable chamber adjacent said first edge, for venting an inflatingmedium away from said base sheet, and away from a second inflatablechamber.
 17. The thermal blanket of claim 16 including an absorbent bibattached to the head end of said base sheet.
 18. A thermal blanket forcovering and bathing a person in a thermally-controlled medium,comprising: a flexible base sheet having a head end, a foot end, twoedges, and a plurality of apertures; an overlaying plastic sheetattached to a first surface of said base sheet by a plurality ofdiscontinuous seams which form said plastic sheet into a plurality ofcommunicating inflatable chambers, said apertures opening through saidbase sheet into said chambers; a continuous seam between said plasticsheet and said base sheet at said head end which forms a non-inflatableviewing recess; and an absorbent bib attached to the head end of saidbase sheet.
 19. A thermal blanket, comprising: a self-erectinginflatable covering with a head end, a foot end, two edges, and anundersurface; an inflating inlet for admitting a thermally-controlledinflating medium; an array of apertures in said undersurface forexhausting a thermally-controlled inflating medium from said covering;an uninflatable section at said head end for upper body viewing; and anabsorbent bib attached to the head end of said inflatable covering.